This invention relates to grain bins, tower dryers, and similar structures having platforms which extend about either the exterior or interior of the structure, or both; and, more particularly, to a catwalk type platform in which the segments forming the catwalk extend radially (inwardly or outwardly) from the side of the structure rather than circumferentially about the structure.
Grain bins, tower dryers, and similar structures are relatively tall buildings having a generally curved sidewall. Access to the structure is typically available at one of several levels extending from the base of the structure to its top. To help people move around the building, platforms commonly referred to as “catwalks” are constructed at each level where access is required. To reach a catwalk, the person climbs a ladder extending from the ground to a top level of the structure, with each intermediate catwalk being accessible to one climbing up or down the ladder. It is known to those skilled in the art that many of these structures have catwalks installed on the inside of the bin or tower, as well as catwalks extending about the outside of the structure.
Catwalks have heretofore been constructed using planks which extend circumferentially about the inside or outside of the building's sidewall. A typical interior catwalk construction is shown in FIG. 1. With respect to FIG. 1, the planks used to form the catwalk are of different lengths. In FIG. 1, a catwalk C1 extending around the interior of a building (not shown) is comprised of three rows of metal planks P1-P3. The planks used for each row are of a different length. That is, the innermost row of planks P1 (the row of planks adjacent the curved outer wall of the structure, is of a first length, the planks P2 forming the second row are of a second and greater length, and the planks P3 forming the outermost row are of an even greater length. Accordingly, to fabricate catwalk C1, one has to have available at least three different size planks.
It will be understood that grain bins, dryers, and similar buildings are not uniform in construction, but may be of different sizes. This means that the manufacture of catwalks for different size structures may require planks of different sizes from the planks P1-P3 shown in FIG. 1. Accordingly, a large number of different size planks must be kept in inventory so to accommodate all the needs of a platform fabricator. Further, as shown in FIG. 2, a catwalk C2 is erected about the exterior of the building. As with catwalk C1, catwalk C2 has three rows of planks P4-P6, the lengths of these planks differing from those of planks P1-P3. Therefore, constructing catwalks on the exterior and interior of the same building requires an even greater number of different size planks which further impacts not only cost, but also ease of construction.
In addition to these issues, manufacturing catwalks using circumferentially extending planks results in an unevenness in the space between the curved outer or inner wall of the building and the planks adjacent the wall. As shown in FIG. 3, the distance D between the side S of the building B and the inner edge of the inner row of planks forming a catwalk varies significantly as one moves around the side of the building. This problem becomes more pronounced for small diameter buildings and creates both a safety issue and a worker effectiveness issue. In the former instance, a relatively large space between the building sidewall and catwalk increases the probability that a tool, for example, can fall from one level to another and injure people working on a lower level, or damage equipment on the lower level. Workers are affected because the gap may mean they cannot put tools or other objects close to the wall or get as close to the wall as they would like to be in order to perform some function (e.g., maintenance). FIG. 3 shows an external catwalk. However, it will be apparent that the same issues are raised with the internal catwalk of FIG. 1.